Former Belleville Mayor Roger Cook (R-Ill.) will challenge Rep. Jerry Costello (D) next year. Cook told the Belleville News-Democrat that he plans to announce his bid for the 12th district Saturday.

The former mayor will face an uphill battle against Costello, a 12-term incumbent representing a marginally Democratic district. 

Cook might have some competition in the primary, too. At least one other Republican, 2010 lieutenant governor nominee Jason Plummer, has already expressed interest in challenging Costello.